Improving solvents



IMPROVING SOLVENTS Filed Jan. 31, 1956 PETROLEUM FRACTI SQLVEN T EXTRACTION 12A F'FINATE. FRACTION SOLUTION 'msTlLLArloN SELECTIVE souvawr EXTRACT 'F'RACTION' .DESTRUCT avg.

HYDROGE NATION D HYDROGENATION SOLVE-NT OIL.

Z QLZKZOMSM Patented May 30,1939

UNITED STATES mmovmc SQLVENTS Per K. Frolich, Westfleld, N. J., assignor to Standard-I. G. Company, a corporation of Delaware Application January 31, 1936, Serial No. 61,755

3 Claims.

The present invention is directed to a method for increasing the solvent power of certain types 7 of solvent and to the improved solvents so produced.

It is known that excellent solvents can be produced from petroleum oils of a certain boiling range by subjecting these oils to extraction with a solvent having a selectivity of the type exhibited by liquid sulfur dioxide and subjecting the extract so obtainedto a treatment known as hydroforming in. which the extract is subjected to the action of hydrogen under a pressure of at least 20 atmospheres and at a temperature ranging from 950 F. to 1050 F. The pressure employed is preferably above 200 atmospheres and the temperature employed is preferably between 975 and 1025 F. The treatment is ordinarily carried out in the presence of a sulfur-immune catalyst of the type known'to be suitable for destructive hydrogenation, preferably one containing a metal of the sixth group of the periodic system or a compound thereof, ior example, molybdenum sulfide, or a mixture of the oxides of molybdenum, zinc and magnesia.

The stock selected as initial material for the production or these solvents is, in general, a cut of a virgin oil having a boiling range from 150 F. to 600 F., preferably from 250 F. to 450 F. and having an aniline point not substantially exceeding 70 F. In the hydroforming, anamount of hydrogen is used such that it exerts a relatively low partial pressure, this amount being not less than 1500 and not more than 6000 cubic ft. of hydrogen per barrel of oil, and for most advantageous operation being between 1500 and 3500 cu. ft. per barrel of oil. The product is usually divided into about four fracti0ns,'each fraction having a particular. field of application as a solvent. The lower fractions are used to the best advantage in lacquers and the upper fractions find their greatest application in -the field of paints and varnishes. products may be found in an article printed at page 693 et seq. of volume 26 of the 1934 edition of Journal of Industrialand Engineering Chemistry by Sw ney and Tilton.

The hydrgzorming step described above is desirably conducted so'as to produce a product which can be divided into four fractions, the first of which has an initial boiling point of 190 F., a final boiling point between 270 and 285 R, an aniline point of 39 F. and a solvent power, as measured on the kauri butanol scale, of 60.2, the second of which has aninitial boiling point between 270 and 280 F., a final boiling point be A full discussion of these 7 (Cl. 196-50) I tween 360 and 385 F., an aniline point of 7 F.

and a solvent power of 75.3, the third of which has an initial boiling point between 360 and 370 F., a final boiling point between 415 and- 425 F., an aniline point of 9 F. and a solvent power of 74.7, and the last of which has an initial boiling point between 415 and 425 F., a

final boiling point of' 550 R, an aniline point of 17- F. and a solvent power of 86.8. The fractions actually obtained do not always have these precise inspections but may overlap any adjacent two of the above listed fractions, It is to the improvement of the solvent power of this hydroformed product or its fractions that the present invention is directed. 1

According to the present invention the solvent power of these hydroformed solvents is considerably increased, in some cases practically doubled, by subjecting said solvents in the vapor phase to the action of a dehydrogenating catalyst, under ordinary, slightly elevated or reduced pressure, and at a temperature between about 900 and 1100 F. The catalyst employed may be any one Phosphates and meta-phosphates as tetralin and decalin. The solvent power of such naphthenes is increased by partial dehydrogenation but complete dehydrogenation to the polynuclear aromatic decreases solvent power. Thus it may be safely said that whatever the nature 'of the stock, the dehydrogenation is discontinued before the formation of normally solid compounds occurs.

In some instances the solvent to be improved may be one from which, on chilling, normally solid constituents may be caused to precipitate. The preferred procedure with such a solvent is to first subject it to hydrogenation under conditions known to be suitable for the hydrogenation of polynuclear aromatics until chilling does not cause a precipitation of normally solid components, and to then subject the solvent to dehydrogenation, in accordance with the present invention, only for such a period that from the prod- The process of the present invention is applicable not only to hydroformed extracts but to hydroformed oils, suitable for use as solvents, in general. Hydroforming, or, as it is sometimes called, hydroaromatization, of any 011 results in the formation of products of a more or less hy-,

hydroaromatic character which, within suitable boiling ranges, are suitable for use as solvents. The utility of all such products for solvent purposes can be-increased by partial dehydrogenation thereof in accordance with the present invention. Ordinarily the hydroformed products suitable for use are those of the boiling ranges previously indicated for solvents obtained by hydroforming extracts.

In a practical embodiment of the present invention a hydroformed sulfur dioxide extract, having a solvent power on a kauri butanol scale of 81.2, an octane number of 81.5, an A. P. I. gravity number of 19.1, and an aniline point of 3.5, was contacted with a catalyst composed of the oxides of chromium, zinc and leadv at a temperature of 1000 F. and under atmospheric pressure at a feed rate of approximately .8 vol. of feed/ volume of catalyst/hour. 4.1% of the feed was lost as gas which was mainly hydrogen. The product obtained had a solvent power, as measured on the kauri butanol scale, of 116.5, an octane number of 86.5, an A. P. I. gravity number of 17.9, and an aniline point of --13' F. The considerable increase in solvent power eflected on this stock is not readily explainable. The decrease in aniline point, presumably representing a conversion of naphthenes to aromatics, does not fully account for the increase in solvent power, nor does the increase in solvent power necessarily follow from the increase in octane number since the factors which influence these two characteristics of the naphtha are in many respects different.

As illustrations of the lack of linear relationship between solvent power improvement, octane number improvement, and aniline point reduction, the following results of two other experi- I ments are oflered. A cracked naphtha having a solvent power of 47.7, an octane number of 77, and an aniline pointof 77 F. was dehydrogenated as described above. The product had a solvent power of 55.8, an octane number of 79, and an aniline point of 50 F. In this case, for a decrease in aniline point of 27 F., the solvent power was increased only 8.1 as against an increase in solvent power of 34.4 for a decrease in aniline of aniline point of 17 F.

The nature and objects of the present invention having been thus described 'and an illustrative embodiment of the same having been given, what is claimed as new and useful and desired to be secured by Letters Patent is:

1. An improved process for producing hydrocarbons of high solvent power from petroleum fractions having a boiling point of about to 600 F., which comprises solvent extracting the petroleum fractions with a solvent having a selectivity of the type exhibited by liquid sulfur dioxide, segregating a portion of lower aniline point than that of the feed from which it is obtained and containing substantial amounts of polynuclear aromatics, subjecting the portion to catalytic destructive hydrogenation under pressures above about 20 atmospheres and at temperatures of approximately 950 F. to 1050 F.'to obtain the conversion of substantial amounts of the polynuclear aromatics to polynuclear hydroaro- 'matics, subsequently dehydrogenating the lastmentioned product at a temperature between,

about 900 F. and 1100 F'.'under approximately ordinary pressure to produce substantial amounts of intermediate partially unsaturated hydro-aromatic products without complete dehydrogenation. to the polynuclear aromatics.

2. An improved process for producing hydrocarbons of high solvent power from petroleum fractions having a boiling point of about 150 to 600 E, which comprises solvent extracting the petroleum fractions with a solvent having a selectivity of the type. exhibited by liquid sulfur dioxide, segregating a portion of lower aniline point than that ,of the feed from which it is obtained and containing substantial amounts of polynuclear aromatics, saturating the portion with hydrogen by catalytic destructive hydrogenation under pressures above about 20 atmospheres and at temperatures of approximately 950 F. to

1050 F. to obtain the conversion of substantial solvent having a selectivity of the type exhibitedby liquid sulfur dioxide, segregating a portion of lower aniline point than that of thefraction from which it is obtained and containing substantial amounts of polynuclear aromatics, subjecting the portion to catalytic destructive hydrogenationunder pressures above about 20 atmospheres and ate. temperature of about 950 F. to 1050 F. until a substantial amount of polynuclear hydro-aromatics is formed and until chilling of the product does not cause precipitation of normally solid components, subsequently dehydrogenating the last-mentioned product at a temperature between about 900 F. and 1100 F. under approximately ordinary pressure to a point Just short of that at which chilling of the product causes the precipitation of normally solid components.

PER K. FROLICH. 

